Purified Escherichia coli recA protein catalyzes homologous pairing of superhelical DNA and single-stranded fragments.

• DOI: 10.1073/pnas.76.4.1638
• Publication Date: 2006-05-31T07:58:12Z
• Authors: T Shibata; C DasGupta; R P Cunningham; C M Radding
• Keywords: Sodium dodecyl sulfate

Purified Escherichia coli recA protein catalyzed ATP-dependent pairing of superhelical DNA and homologous single-stranded fragments. The product the reaction: (i) was retained by nitrocellulose filters in 1.5 M NaCl/0.15 Na citrate at pH 7, (ii) dissociated 12.3 but not heating 55 degrees C for 4 min or treatment with 0.2% sodium dodecyl sulfate proteinase K, (iii) contained covalently closed circular double-stranded (form I DNA), (iv) fragments associated replicative form (RF) DNA, (v) a significant fraction D-loops as judged electron microscopy. Linear nicked did substitute well DNA; intact Homologous combinations from phages phiX174 fd reacted, whereas heterologous not. reaction required high concentrations MgCl2. ATPase activity purified more than 98% dependent on addition DNA. In 1 mM MgCl2, ability to support two-thirds good that